Water-felted building product including nonfibrous cellulose binder



Apri 23, wss

R. ROBERTS WATER-FELTED BUILDING PRODUCT INCLUDING NONFIBROUS CELLULOSE BINDER Filed Jan. 16, 1964 mv MTNOFM vim. uv .PDU

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INVENTOR.

United States Patent O 3,379,609 WATER-FELTED BUHJDING PRODUCT INCLUD- ING NONFIBROUS CELLULOSE BINDER James R. Roberts, Palatine, Ill., assigner to United States Gypsum Company, a corporation of Delaware Filed Jan. 16, 1964, Ser. No. 338,057 8 Claims. (Cl. 162-181) ABSTRACT F THE DISCLOSURE A building product comprising expanded perlite, and a water-activated cellulose binder which is essentially nonfibrous in character.

This invention relates to the production of unied monolithic building products and more particularly to improved unified, lightweight building products in sheet form containing perlite and a cellulosic binder.

lExpanded perlite is a well known commercial lightweight mineral aggregate, produced by the thermal expansion of the volcanic glass perlite. The product is cellular or vesicular in form, ordinarily having an essentially sperical shape. Generally the product produced by commercial operations contains a bro'ad range of particles sizes.

Building products containing expanded perlite and fibrous materials such as paper pulp are also known. For example; prior art discloses insulating bo'ard products made from expanded perlite and newspaper pulp by accumulation on a cylinder machine from a slurry in a manner similar to paper manufacture. While these products have merit as insulating materials, it has been found that they lack sufcient structural integrity for certain purposes land do not have the necessary surface properties for use as yfinished Wall or ceiling surfaces on resident or commercial construction. None of these products had any particular resistance to abrasion or compression.

Some attempts have also been made to improve the structural integrity of perlite-paper pulp products by the use of binders such as asphalt and other organic material such as starch, polymers and the like. While these expedients had some success in improving integrity of the product, they also changed the appearance and other properties of the product with respect to color, weight or lire resistance.

Accordingly it is an object of the present invention to provide an improved unified monolithic building product in sheet form which has characteristics of lightweight and superior strength.

A further object is the provision of a building product which has superior compression and abrasion resistance.

A still further object is the provision of a building product which has excellent structural integrity Iachieved without the use of synthetic organic fibers, asphalt or other synthetic binders.

Another object is the provision of a monolithic building product which has excellent fire resistance.

Another object is the provision of a monolithic building product in sheet form which has improved sound absorption and attenuation properties.

Another object is the provision of a unified building product in sheet form which has surfaces which are 'adapted for finishing.

Another object is the provision of a building product in sheet form Which has superior thermal insulating properties.

The fulfillment of these and other objects of the present invention may be seen from the following specification and appended claims.

Accordingly in one broad form the present invention 3,37%,609 Patented Apr. 23, 1968 rice comprises ya unified lightweight monolithic building product in sheet form, said unified product comprising one part of a mechanically induced w'ater activated cellulosic binder and from about 5/3 to 9 parts by weight (dry basis) of a thermally expanded perlite. Preferably the proportions of perlite range from 7/3 to 8.5 parts.

In another broad form the present invention comprises building products which contain 'a minor proportion of a ceramic clay, specifically up to about 2 parts clay per part of cellulostic binder, and in the most preferred instances from 1/3 to 2 parts of clay per part of cellulosic binder.

The foregoing compositions may also optionally contain boric 'acid as a re retardant and small amounts of a wax for water repellancy. Waxes, such as microcrystalline wax, petroleum Wax, paraflin waxes and the like, are suitable. The wax, when used, is usu'ally in amounts up to about 2 percent by weight and preferably from 0.25 to 1 percent by weight. The boric acid is ygenerally incorporated into the product in amounts up to 3 percent by weight, and preferably from 0.25 percent to 2 percent. Alum may also be incorporated for superior processing in amounts of from about 1/2 to 11/2 percent. The minor additives, i.e. boric acid, wax and alum, are expressed as percentages of the total product weight. All parts and percentages referred to herein, unless otherwise stated, should be understood to be on a dry weight basis.

Generally the products of the present invention are lightweight, i.e. having densities in the broadest aspects of from about 4 to about 25 pounds per cubic foot, prefer'ably from 8 to 20 pounds per cubic foot.

The proportions of the components of the products of the present invention -can be more particularly defined in terms of percent by weight. Broadly these products contain from 50 to 90 percent perlite, from 10 to 30 percent cellulosic binder and from zero to 2O percent clay. For example, those embodiments which consist essentially of cellulosic binder and perlite broadly contain from 70 to 90 percent perlite, from 10 to 3G percent cellulosic binder. These products are eminently suitable for applications as insulating'floor underlayment, ceiling or wall tile or insulating board. They are characterized by superior compressive strength and resistance to abrasion, sharp blows and abuse. These particular qualities of a high perlite product make possible applications for a thermal insulating door underlayment for surfacing with wood or plastic tiles that will stand up under the stress of floor traic. This product may also be used in Wall insulation and in tiles showing superior performance in the area of insulation and reduction of sound transmission. This latter property is especially valuable in modern commercial buildings which feature suspended ceilings and non-loadbearing partition walls. Ordinarily in such construction the ceilings and walls are formed of tile or board. With the superior sound attenuation and deadening properties available in these products the amount of sound transmission through the ceiling and walls into adjacent 'areas is substantially reduced, especially in those board products containing a high proportion of perlite.

The compositions o-f the present invention which contain clay in addition to perlite and cellulosic binder are especially useful in lire resisting applications. The clay used is of the high alumina and silica, ceramic variety and is characterized as nonswellinig. Clays, such as kaolin, fire clay, brick clay and ball clay, are exemplary. The iirst resistant building product contains from about 50 to 80 percent perlite, from l() to 3'0' percent cellulosic binder and from 10 to 20 percent ceramic clay. The clay is especially valuable in the production of fire rated tile. Thus, when subjected to fire, the clay containing tiles or wallbo'ard products sinter, rather than spall or undergo 3 gross delamination or support combustion, as in the case of other materials.

The products of the present invention may, as previousiy pointed out, also be used in the production of building materialsl for sound` and thermal insulation wherein the surface is exposed to view.

Particular reference is also made to ceiling tile or board products of the present invention which may be painted, or if desired surfaced on one or both sides with paper sheets to form a laminated or sandwich construction. The products may also be used to prepare acoustical, drilled or perforated tile by conventional techniques.

The perlite which is used in the products of the present invention may be of a variety of mesh sizes. Generally mesh sizes of less than 8 mesh are suitable for structural insulating boards and underlayrnent. For those applications which require a smooth finish on the surface of the product, i.e. ceiling tile, it is preferred to use a finer perlite, preferably one in which at least 70 percent passes a mesh screen, and which has no particles larger than 8 mesh (US. Standard Sieve Series).

The cellulosic binder, the manufacture of which is one aspect of this invention, is a highly hydrated gelatinous substance. The starting material may be any cellulosic material, preferably an unbleached waste lkraft stock. lt has been found that extended refining of the pulp results in a change of properties and the cellulose is converted thereby from a fibrous material to an essentially nonfibrous gelatinous substance. With this refining treatment it has been found that the properties of the cellulose change to such an extent that the material acts essentially 'as an adhesive without liber interfeltinlg action. The degree of hydration may be expressed in terms of Schopper-Riegler freeness. Preferably the products of the present invention are mechanically hydrated to a Schopper-Riegler freeness of less than about 100 m1. and preferably less t-han about 90 ml. The increasing hydration results in superior strength of the products when the cellulose material is used in the products of the present invention. The effect of the refining or Schopper-Riegler freeness is shown in the subjoined table.

TABLE L FREENESS VALUES OF CELLULOSE BINDERS 1Sce Forest Products Laboratory Report No. 884, reaffirmed 1956. Also, Schaeffer and Carpenter, Paper Trade Jr. May 1930.

2 After rcpulpng: consistency 6-S+.

The series refining steps referred to in the above table are passes of the pulp through a Morden Stockmaker type pulp renner equipped with lava tackle.

For a better understanding of this invention, reference is made to the accompanying drawing, illustrating in flow sheet form the sequence of steps involved in the process of the present invention, Referring to that drawing there is illustrated a paper source, preferably yan unbleached waste kraft paper source, which discharges into a hydropulper of the Morden Slushmaker type, and water is added to form a kraft paper fiber furnish having a consistency of at least about 6 percent. The discharge from the hydropulper is passed to a stock tank and then through a series of pulp refiners (A, B, C, D), such as preferably of the Morden type equipped with lav'a tackle. The pulp from refiner A is discharged into a refiner B and thence to refiners C and D in cascade sequence with a total residence time of about 15 seconds. The final product has a Schoppler-Riegler freeness of less than about 100. The cellulosic binder discharge from the reiiner sequence is highly hydrated and essentially nonfibrous in character. The cellulosic binder is passed to a stock tank for storage and supply. At intervals the cellulosic binder is passed to a mixing chest where perlite in the desired amount is added. Clay from source may also be added to the mix if desired in the particular embodiment. Water may be added from the source to adjust the con-sisten-cy of the mix to from about 4 to about 8 percent although the consistency may also be adjusted in the furnish making stage. Other additives, such as bon'c acid, Wax, and alum, as desired, may be added at this point. After mixing to form a uniform slurry, the contents of the mixing chest are discharged to the machine chest and thence onto the screen of the Fourdrinier machine. Other types of paper, board or sheet making machines, such as cylinder machines and the like may be employed, if desired. The slurry of cellulosic binder, perlite, and/or other additives is deposited or laid on the screen or wire in an initial thickness of from about 3A to 4 inches. The web thus formed is compacted in the press section by roller presses or the like to a thickness of from about 1/2 to 11/2 inches, and thence to 'a drier, preferably of the multiple deck variety. The dried product in sheet form is trimmed and cut to the desired size and passed to a storage or for further finishing, such as by painting, lamination of paper sheets on one or both surfaces, larninations of the sheet, perforations, or the like.

Insulation products were made by the process of the present invention containing varying amounts of perlite, cellulosic binder, clay and other additives. Each product was laminated with paper sheets on both surfaces to illustrate the results obtained with the laminated as compared with the unlaminated product. The following examples illustrate the composition and physical properties of the sheet products made in accordance with this invention.

COMPOSITION 0F SHEET [All of the sheets were produced in a dry thickness ranging from 0.71 to 0.75 inch] Perlite 1 Cellulosic Clay 3 Binder' 2 UNLAMINATED SHEETS MOR 4 Density 5 Hardness 5 LANHNATED SHEETS 7 MOR 4 Hardness 5 Example:

1 Parts by Weight (dry basis). Screen analysis: +20 mesh 0%; +50 mesh 7.8%; mesh 36.2%; +200 mesh 28.4%', 200 mesh 27.6%.

2 Parts by weight (dry basis). Initial consitenoy, 6%. Schepper-Riegler Frceness less than 100.

3 Parts by Weight. Kentucky-Tennessee Clay Co. (CTS-1). Silica. 57.0%; Alumina 27.9%', Loss on ignition 9.8%.

4 Modulus of Rupture, Pounds per square inch.

Pounds per cubic foot.

Force in pounds required to force a 2 inch diameter steel ball l/. into the surface of the sheet.

7 Laminated on both surfaces with manila faced shipboard sheet having a weight of 72 pounds per 1,000 square feet. Polyvinyl acetate adhesive (Du Pont Elvacet) inch Example 7 This example illustrates the commercial production of a lightweight insulation product of the present invention which has utility as a sound deadening board. The preparation follows the procedure described above. The following table shaws the proportions of each component in the final product in terms of percentage composition and weight.

25,600 pounds of water and 1,600 pounds of unbleached waste kraft paper were introduced into a Morden Slushmaker and rened for 30 minutes. The resulting fiber furnish was passed into a stock tank and thence through a sequence of four Morden paper refiners (a throughput time of 60 minutes per ton).

The water activated cellulose binder from the last refiner had a Schopper-Riegler freeness of less than 100. The cellulosic binder dispersion at a consistency of about 6 percent was passed to a stock tank and then to a mixing chest for admixture with water (166,400 pounds), clay, perlite, boric acid, wax and alum in the amounts indicated. The perlite had a mesh size range of about -20 to +200 (70%). The clay was a ceramic type ball clay (Kentucky-Tennessee Clay Co., CTS-1) having the following analysis:

Percent SiO2 57.0 A1203 27.9 Ignition loss 9.8

The wax was a microcrystalline wax-Mobil Oil Co. Mobilcere-RV emulsion.

The product from the mixing tank with a consistency of about 4 percent was passed to the Fourdrinier machine and formed into a sheet which, after pressing and drying, had a thickness of about 3%; inch. The final product, when cut and trimmed, had a density of 14 pounds per cubic foot.

The products of the present invention are characterized by excellent fire resistance. For example, the products containing perlite, binder and clay have a class 1 rating by ASTM E84-61 (Underwriters Laboratories Standard 723). The products also have a Class A rating according to Federal Specification SS-A-00l18c (Apr. 14, 1960).

As may be appreciated the cellulosic binder material and the water felted insulating and building products of the present invention are readily prepared in a variety of forms by the processes outlined above. The method described may also be modified with respect to .the equipment used in manufacture, such substitution being conventional in this art.

While several particular embodiments of this invention are shown above, it will be understood, of course, that the invention is not to be limited thereto, since many modifications may be made, and it is contemplated, therefore, by the appended claims, to cover any such modifications as fall within the true spirit and scope of this invention.

I claim:

1. A method of producing a unified monolithic building product in sheet form which comprises forming a gelatinous cellulosic binder by dispersing a kraft fiber in water to form a slurry of up to about 6% consistency, continuously passing the slurry through a series of pulp refiners having abrading surfaces preset to gelatininizing conditions for a time and an intensity to produce an essentially nonfibrous gelatinous slurry having a Schopper- Riegler freeness of up to about m1., and a patricle size on the order of up to about 0.06 mm., admixiug the resulting slurry with from 5/ 3 to 9 parts of a thermally eX- panded perlite per part of binder (dry basis) to form an aqueous slurry of a consistency of from 4 to 8 percent, the major proportion of said perlite having a particle size of greater than 200 mesh, forming a felted sheet from said admixture, compressing the felted sheet to expel eX- cess water, and drying said sheet.

2. The process of claim 1 wherein the proportion of thermally expanded perlite admixed with cellulosic binder is from about 7/ 3 to 8.5 parts of perlite per part of cellulosic binder (dry basis).

3. The process of claim 1 wherein a wax emulsion in an amount of up to about 2 percent by weight (dry basis) is added to said aqueous admixture.

4. The process of claim 1 wherein the abrading surfaces are lava.

5. A lightweight unlied monolithic building product in sheet form, said unified product comprising a mechanically induced water activated cellulosic gelatinous binder having a Schopper-Riegler freeuess in its original hydrated state of less than about 100 ml. and prepared from a slurry of kraft paper fibers of a consistency of up to about 6 percent which is subsequently gelatinized by passage through a series of paper refiners preset to gelatinizing conditions to produce a cellulosic binder having an average particle size on the order of up to about 0.06 mm., and from 5/ 3 to 9 parts of a thermally expanded perlite, the major proportion of which has a particle size of greater than 200 mesh, said unified product being further characterized in that the unification is provided by the essentially noniibrous substance acting essentially as an adhesive without fiber interfelting action.

6. The product of claim 5 containing a minor proportion, with respect to the amount of perlite, of ceramic clay.

7. The product according to claim 5 wherein the thermally expanded perlite is present in proportions of from about 7/ 3 to 8.5 parts per part of cellulosic binder (dry basis).

8. The product of claim 5 wherein a paper sheet is laminated on at least one surface of said dried sheet.

References Cited UNITED STATES PATENTS 2,426,923 9/ 1947 Cowles 16,2-187 2,634,207 4/ 1953 Miscall 162-181 2,971,878 2/1961 Heilman et al. 162-181 X 3,001,907 9/1961 Bergstrom 162-181 X 3,066,065 11/ 1962 Koerner et al 162-187 X DONALL H. SYLVESTER, Primary Examiner.

HOWARD R. CAINE, Examiner. 

